FindJsonCpp: add imported targets

CMake/FindJsonCpp.cmake

-# Find the JsonCpp include files and library.
-#
-# JsonCpp is a C++ library that can read/write JSON (JavaScript Object Notation)
-# documents. See http://jsoncpp.sourceforge.net/ for more details.
-#
-# This module defines:
-# JsonCpp_INCLUDE_DIRS - where to find json/json.h
-# JsonCpp_LIBRARIES - the libraries to link against to use JsonCpp
-# JsonCpp_FOUND - if false the library was not found.
-
 find_path(JsonCpp_INCLUDE_DIR "json/json.h"
   PATH_SUFFIXES "jsoncpp"
-  DOC "Specify the JsonCpp include directory here")
+  DOC "jsoncpp include directory")
+mark_as_advanced(JsonCpp_INCLUDE_DIR)
 
 find_library(JsonCpp_LIBRARY
   NAMES jsoncpp
-  PATHS
-  DOC "Specify the JsonCpp library here")
-set(JsonCpp_INCLUDE_DIRS ${JsonCpp_INCLUDE_DIR})
-set(JsonCpp_LIBRARIES "${JsonCpp_LIBRARY}")
-
-set(_JsonCpp_version_args)
-if (EXISTS "${JsonCpp_INCLUDE_DIR}/json/version.h")
-  file(STRINGS "${JsonCpp_INCLUDE_DIR}/json/version.h" _JsonCpp_version_contents REGEX "JSONCPP_VERSION_[A-Z]+")
-  foreach (_JsonCpp_version_part MAJOR MINOR PATCH)
-    string(REGEX REPLACE ".*# *define +JSONCPP_VERSION_${_JsonCpp_version_part} +([0-9]+).*" "\\1" JsonCpp_VERSION_${_JsonCpp_version_part} "${_JsonCpp_version_contents}")
-  endforeach ()
-
-  set(JsonCpp_VERSION_STRING "${JsonCpp_VERSION_MAJOR}.${JsonCpp_VERSION_MINOR}.${JsonCpp_VERSION_PATCH}")
+  DOC "jsoncpp library")
+mark_as_advanced(JsonCpp_LIBRARY)
 
-  set(_JsonCpp_version_args VERSION_VAR JsonCpp_VERSION_STRING)
+if (JsonCpp_INCLUDE_DIR AND EXISTS "${JsonCpp_INCLUDE_DIR}/json/version.h")
+  file(STRINGS "${JsonCpp_INCLUDE_DIR}/json/version.h" _JsonCpp_version_lines
+    REGEX "JSONCPP_VERSION_[A-Z]+")
+  string(REGEX REPLACE ".*# *define +JSONCPP_VERSION_MAJOR +([0-9]+).*" "\\1" _JsonCpp_version_major "${_JsonCpp_version_lines}")
+  string(REGEX REPLACE ".*# *define +JSONCPP_VERSION_MINOR +([0-9]+).*" "\\1" _JsonCpp_version_minor "${_JsonCpp_version_lines}")
+  string(REGEX REPLACE ".*# *define +JSONCPP_VERSION_PATCH +([0-9]+).*" "\\1" _JsonCpp_version_patch "${_JsonCpp_version_lines}")
+  set(JsonCpp_VERSION "${_JsonCpp_version_major}.${_JsonCpp_version_minor}.${_JsonCpp_version_patch}")
+  unset(_JsonCpp_version_major)
+  unset(_JsonCpp_version_minor)
+  unset(_JsonCpp_version_patch)
+  unset(_JsonCpp_version_lines)
 endif ()
 
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(JsonCpp
-  REQUIRED_VARS JsonCpp_LIBRARIES JsonCpp_INCLUDE_DIRS
-  ${_JsonCpp_version_args})
+  REQUIRED_VARS JsonCpp_LIBRARY JsonCpp_INCLUDE_DIR
+  VERSION_VAR JsonCpp_VERSION)
 
-mark_as_advanced(JsonCpp_INCLUDE_DIR JsonCpp_LIBRARY)
+if (JsonCpp_FOUND)
+  set(JsonCpp_INCLUDE_DIRS "${JsonCpp_INCLUDE_DIR}")
+  set(JsonCpp_LIBRARIES "${JsonCpp_LIBRARY}")
+
+  if (NOT TARGET JsonCpp::JsonCpp)
+    include(vtkDetectLibraryType)
+    vtk_detect_library_type(jsoncpp_library_type
+      PATH "${JsonCpp_LIBRARY}")
+    add_library(JsonCpp::JsonCpp "${jsoncpp_library_type}" IMPORTED)
+    unset(jsoncpp_library_type)
+    set_target_properties(JsonCpp::JsonCpp PROPERTIES
+      IMPORTED_LOCATION "${JsonCpp_LIBRARY}"
+      INTERFACE_INCLUDE_DIRECTORIES "${JsonCpp_INCLUDE_DIR}")
+  endif ()
+endif ()